CHAPTER 6: VIDEO

ITBIS351 Multimedia Systems and Hypermedia

Yaqoob Al-Slaise

OUTLINE

VIDEO

O

f all the multimedia elements, video

places the highest performance

demand on your computer or device

—and its memory and storage.

W

hen light reflected from an

object passes through a video

camera lens, that light is

converted into an electronic

signal by a special sensor

called a

c

harge-coupled device (CCD)

HOW VIDEO WORKS

A

nalog video has a

resolution measured in

the number of horizontal

scan lines (due to the

nature of early cathode-

tube cameras).

ANALOG VIDEO

C

omponent: Separates the

Red, Green, Blue channels

on different CCDs as

separate signals on its own

conductor.

Component is used for high

quality video.

VIDEO STANDARDS (COMPONENT)

S

-Video: (Separate Video)

uses two channels:• Luminance:

sometimes referred as Y (greyscale).

• Chrominance: sometimes referred as C (color)

S-VIDEO

C

omposite: when all the

signals are mixed together

and carried on a single cable

as a composite of the three

color channels and the sync

signal. The composite signal

yields less-precise color

definition.

COMPOSITE

A

single video frame is made up

of two fields that are

interlaced.

T

racking is the fine adjustment

of the tape during playback so

that the tracks are properly

aligned as the tape moves

across the playback head.

HELICAL SCAN

N

TSC

ANALOG BROADCAST STANDARDS

N

ational Television Standards

Committee

a

single frame of video was made up of

525 horizontal scan lines drawn onto

the inside face of a phosphor-coated

picture tube every 1/30th of a second

by a fast-moving electron beam.

O

dd lines than even lines (60 lines per

second= 60Hz)

FLICKERING

P

AL

ANALOG BROADCAST STANDARDS

P

hase Alternate Line (PAL)

i

ncreased the screen resolution

to 625 horizontal lines, but

slowed the scan rate to 25

frames per second.

5

0 lines per second = 50Hz

S

ECAM

ANALOG BROADCAST STANDARDS

S

equential Color and Memory

(SECAM)

a

625-line, 50 Hz system.

S

ECAM transmits only one color at

a time, it is free of the color

artifacts present in NTSC and PAL

resulting from the combined

transmission of both signals.

ANALOG BROADCAST STANDARDS

DIGITAL VIDEO

HDTV

H

DTV provides high resolution in a 16:9 aspect ratio.

T

he broadcast industry promulgated an ultra-high-resolution, 1920 × 1080

interlaced format (1080i).

B

UT the computer industry wanted a 1280 × 720 progressive-scan system

(720p) for HDTV.

B

oth formats have been included in the HDTV standard by the Advanced

Television Systems Committee (ATSC).

DISPLAYS

DISPLAYS

c

athode ray tube (CRT): Colored phosphors screen

glow red, green, or blue when they are energized by

an electron beam.

DEGAUSSING

FLAT SCREEN

L

iquid-crystal display (LCD) is a flat panel display, electronic visual

display, or video display that uses the light modulating properties of

liquid crystals. Liquid crystals do not emit light directly.

P

lasma: the technology utilizes small cells containing electrically

charged ionized gases, or what are in essence chambers more

commonly known as fluorescent lamps.

INTERLACING

COMPARISON

OVERSCAN/ UNDERSCAN

MPEG

MPEG-1 MPEG-2 MPEG-4

• 1.2 Mbps of video

• 250 Kbps of two-channel stereo audio using CD-ROM technology.

• higher data rates (3 to 15 Mbps).

• higher image resolution.

• multiresolution scalability.

• Standard for Digital TV and DVDs.

• It offers indexing, hyperlinking, querying, browsing,

uploading, downloading.

• Virtual Reality

SHOOTING AND EDITING VIDEO

F

ast processor(s)

P

lenty of RAM

C

omputer with FireWire (IEEE 1394 or i.Link) or USB connection and cables

F

ast and big hard disk(s)

A

second display to allow for more real estate for your editing software

E

xternal speakers

N

onlinear editing (NLE) software

SHOOTING PLATFORM

STORYBOARD

CHROMA KEY

C

hroma keys allow you

to choose a color or

range of colors that

become transparent,

allowing the video image

to be seen “through” the

computer image.

WHITE BALANCE

LINEAR EDITING

NON LINEAR EDITING